The main objectives of this study are to see if a type of lung surgery, known as lung reduction surgery, in addition to standard medical treatment improves the quality of life, lung function, and reduces the high mortality associated with severe emphysema when compared to standard medical treatment alone. Another goal of this study is to better identify the patients most likely to benefit from this surgical treatment. The information obtained in this study is important because lung reduction surgery is being done in several centers around the country but its long term benefits, if any, over standard medical treatment, are not known.